Hygrometer



Aug. 6, 1935. W 0 mum HYGROMETER Filed May 25, 1931 INVENTOR m/o/ifi/ 6 6055 BY I @%W A TTORNEY This invention relates to indicators Patented Aug. 6,1935

OFFICE HYGROMETER Worth C. Goss, Seattle, Wash., assignor to Humidity Control Company a Application May 25, 1931, serial No. 539,694

and it has reference particularly to improvements in indicators, controllers andthe like, of that charac-j ter now employed quite {extensively for humidity control or for indicating changes in relative hu-,

midity of .the atmosphere, andwhich in their construction employ a pointer, ,that is movable under the control, or a hygroscopic material,

which by reason of its physical characteristics or properties is, caused to change form in accord ance with the changes in relati'vehumidity, and thus to move the pointer to indicate the extent of'the change; i I

Explanatory to theinyention, it will here be stated that indicating devices "of the general character above outlined have proven to be very sensitive to changes in relative humidity and thus are very desirable," but by reason of the natural fatigue, or; stretch of, any hygroscopic material when under constant tension, soon become out of adjustment and must of necessity becarefully readjustedin order that theywill be accurate to a reasonable'degree; When such adjustment is not properly made, the instrument will notbe accurate or dependable in its readings and furthermore, there is always the uncertainty where a a h groscopicmaterial; is used, of not knowing whether-or not the instrument isin orvout of proper adjustment. T i In view of the aboveyit has been theprincipal object of thisrinvention to provide; an indicator .ofthe above character which may operateunder the control of any suitable hygroscopic ,rnaterial such as a hair belt'or the like, in the usual manner, but which includes additionalmeans whereby the instrument isautomatically maintained in accurate adjustment regardless of fatigue of thematerial.

wherein- 1 g a j j T e le figure is an elcvation oi an indicator f More" specifically stated, the invention resides inthe provision of a compensating means for automatically readjusting to :correct inaccuracies that would arise dueto the fatigue in the hygro- V scopic material, so thatafter the instrument once is properly adjusted for use, practically no further-adjustment or attention is required. Y tOtherobjects of theinvention reside inthe details of onstruction and combination of parts, .as hereinafter described.

InQaccomplishing these and other objects of j the invention, I have provided the improved de- 1 tails of construction, the preferred forms of which are illustrated in the accompanying drawing,

directed legs 4 and 4a which are slightly longer attached to the base member I. 1 under tension connects with the lower end of the leg 4 at'la and with the pointer at lb which is at a predetermined distance below the pivot 3 7 Claims. (01. 73-24) having an automatic adjustment embodied by the present invention. s l i It is thought Well to here state that the present drawing is not intended to setforth a definite construction which must be followed in order to carry out the invention, but is for the purpose of illustrating the principle on which this invention is based and to show a construction that is satisfactory for carrying out the invention; it being understood that there may be modifications in form, size and in the proportion of the various parts used, so long as these changes do not cause adeparture from the principle ,onwhich the device is based. s Referring more in detail to the drawing-- n! designates a base, frame or other suitable backing member for mounting the various parts of the instrument. Supported on this frame is a horizontal lever 2 supported for pivotal action by a pivot pin 3 that isiixed in the base I. In the present instance the pivot pin 3 about which the lever 2 operates is disposed at a distance from oneendof the lever which is approximately twice its distance from the other end and for convenience in the description the long and short 25 end portions at opposite sides of the pivot will be referred to as the long and short arms of the lever. a

At its opposite ends the lever has downwardly than the short arm above referred to.

A pointer 5 is extended downwardly from the pivot pin 3 and this is arranged to follow along an arcuate, graduated plate or strip 6 which is A coiled spring Likewise, a belt 8 of hygroscopic material under tension connects at one end as at 8a with the leg 4a of the lever 2, and also with the pointer at lb,

so that the pointer, by reason of spring 1 and belt 8,- will move about the pivot in accordance It will be noted that the points of connection 50 :1a and 1b ofthe opposite endsof the spring with the leg 4 and pointer 5, and the points of connection 1b and Ba of the opposite ends of the -belt 8-with the pointer and leg 4a are in alignment .and thatthis alignment is parallel with the lever 2, and that the connection retains the pointer substantially at a right angle to the lever l.

In use of the device, the lever 2 is moved to adjust the position of the pointer 5, under conto the distance from the pivot 3 to the point of connection lb of the spring I and belt 8 with the pointer 5. The upper end' of the belt I2 is attached to an adjusting screw l5, mounted in a supporting bracket 18 fixed to the base member I. The pull of the belt 12 on this endof the lever is counterbalanced by the pull of a'coiled spring is that is disposed parallel to the belt l2 and attached at its upper end to a fixed pin ISand at its lower end toa pivot '20 in the lever 2 at a distance from the pivot 3 equal to thedistance between the pivot 3 and connection l4.

Since I have employed a hygroscopic material in the instrument to compensate for error due to fatigue in thehygroscopic material which controls the action of the instrument, there must be a definite relationship in the belts themselves and springs used to counterbalance them. Also, it is very important to proper operation of the instru r'nentthat the two hygroscopic belts be of ma terial or materials having identically 'the same characteristics and thatthe relationship of their lengths shall govern the relationship of the springs employed. For example, if the belt 8 is one-third the length of the belt l2, and both have the same physical characteristics, then the,

tension of the spring 1 shall be three times that of the spring 18. Likewise, if the belt 8 is onehalf the length of the belt 12, the spring I8 shall have a tension equal to one-half that of the spring I. It must be understood, however, that these requirements are based on an instrument in which the points of connection lb-l4 and 20 are at equal distance from pivot 3. A change in this condition would necessitates compensating change'in length of belts or tension of springs in order that the fatigue in belt 8 would automatically compensatefor any error by reasonof fatique in belt l2. f r n v To use the device as 'an indicator, it should first be adjusted to a standard or an accurate instrument. Then it is quite apparent that changes inrelative humidity of the atmosphere'will effect the belt l2 in a manner to permit movement of the lever 2 pivotally on its supporting pin 3 and thereby cause movement of the pointer 5 along the graduated scale plate 6 to indicate the changes in the relative humidity. Should the pointer 5 be rigidly flxedto the lever 2, it is obvious that its movement would be exactly in accordance with the movement of the lever 2, but in the present instance it'is quite apparent that changes in relative humidity' which affect the length of the belt l2 will likewise affect the length of the belt 8, and that the pointer willnot move as far as it would if rigidly fixed to the lever. However,

it must be remembered that thescale plate 6' is graduated in a manner to reckon with the changes permitted by reason of the belt 8 and therefore the readings will be just as accurate as if the belt 8 were not used. n p

In the present construction, any stretch or' .75 "fatigue in the belt 12 is compensated for by reason of a corresponding fatigue in the belt 8.

For instance, should the belt [2 under tensionof spring I8 stretch a certain distance, the belt-8 under tension of spring 1 will stretch the same -distance.- Therefore, any inaccuracy of the instrument by reason'of stretch in the belt 12 which would permit the'pointer to swing farther toward the right hand side, would be compensated for in a corresponding stretching of belt 8 which would permit the pointer to swing toward leg 4 of. the lever. This result is byreason of that definite relationship that exists .between the two hygroscopic'belts employed, the definite relationship in lengths of lever arms and a proper proportioning of spring tensions in accordance with the leverage and pull of the belts.

It is quite obvious that various arrangements other than that shown might be employed, there-' fore I do not wish to confine, my claims only to that'shown but desire that they shall apply to all modifications thereof so long as they employ an equivalent arrangementldiffering. only in the proportioning of belts, springs or leverage; v 'Having'thus described my invention, what I claim as new therein and-desire to secureby Letters Patent isl. An'instr ument of the character described comprising a rocker'having a supporting pivot, a spring'and a hygroscopic belt connected in opposed relation to the rocker to controlits action, a lever mounted to moveon'the-pivot; aspring and a hygroscopic beltfcormected tothe'rocker and to the lever in opposed relation to cause the lever to swing on the-pivot in accordance with movement of the rocker; said second mentioned hygroscopic belt being adapted to automatically effect adjustment of 'theile'ver' reldtiveto the rocker to compensate for movement of the rocker dueto fatigue in the first mentioned 'beltq' '2. An instrument of' the character described comprising a leverpivotally mounted ata point intermediate'its ends, a spring anda hygroscopic belt-connected to the lever at opposite sides of thepivotin opposed relation and whereby movement of the lever is governed byv the elongation'or contraction-of the hygroscopic belt, a pointer movable onthepivot free 'of the lever, a spring and a hygroscopicbelt connected to the lever at opposite sides'of the pivot and to the pointer in opposed relation and effecting movementof the pointer with the clever; said belts having'ideritical characteristics and being under correspond- 'ingstrain incident: to their use wherebyany movement of the lever by reason of fatigue of the first mentioned belt will be compensated for by a corrective movementof the pointer b reason of fatigue n the second belt.

comprising a lever having a pivotal support iiilever at one sideof the pivot, a 'hygroscopicbelt connected to the'lever at the'other side of the freely of the lever and extended substantially at a right angle to the lever, a spring and'hygro-' scopic belt connected. tothe'pointer in opposed to move with the lever, said-last mentioned'belt being adaptedby elongation incidenteto fatigue,

to permit movement of the pointer that will coinpensate for movement of the lever due, to fatigue in the first mentionedbelt.

3. An instrument of the character described 7 termediate its ends, a spring connected to the f relation and to the lever to cause the pointer 4, An instrument of the character described comprising. a horizontally. disposed lever having supporting the said lever intermediate its ends, a spring attached to the lever at one side ofthe pivot, a belt of hygroscopic material attached to the lever at the other side. of thepivot to oppose the pull of said spring, a pointer mounted on the to that leg ofdthe lever at the end to which the hygroscopic belt is attached a belt of hygroscopic material attached to the other leg of the Q lever anci'to the pointer to oppose the tension of the second mentioned spring, the latter belt being shorter than that first mentioned and held under atensionthat is such by reason of the connections that elongation dueto fatigue in the belt will effect a corrective movement of the pointer relative to the lever that will compensate for movement of the lever due to fatigue in the first belt.

5. An instrument of the character described comprising a horizontally disposed lever having downturned legs at its opposite ends, a pivot pin supportingth'e lever at a point between its ends, a spring and abelt of hygroscopic material connectedto the lever at equal distances fromthe pivot to oppose each otherand to cause movement of the lever by reason of contraction or elongation of the belt, a pointer mounted on the pivot free of the leverjand extended downwardly therefrom, a spring and a belt of hygroscopic ,material attached tothe pointer at a distance from the pivotequal tothefdistancefrom the pivot to. the point of attachment of the first spring with the lever, and connected respectively to the opposite legs of the leverto oppose each other and to cause movement of the pointer with the lever, the second mentioned belt having char- I acteristics like that of the first but being of lesser length, and the tension ofthe first mentioned spring bearing the same proportion to that of the second as the length of the second 1 belt is to the length of the first belt. pivot free of the lever and extended downwardly therefrom, a spring attached to the pointer and 6. In aninstrument of the character described, a movably mounted pointer, a yieldingly movable lever, a hygroscopic element associated under tension with the lever and operable to cause movement thereof in accordance with humidity changes, a hygroscopic element associated under tension with the lever and pointer whereby the pointer willbe caused to move with the lever;

the tension on the second hygroscopic element being such as to cause an elongation from fatigue with a resultant change in adjustment between the pointer and lever thatwill compensate for elongation of the. first recited ment from fatigue therein.

7. An instrument of the character described, comprising a pivoted lever, a hygroscopic belt hygroscopic eleconnected under tension with the lever for moving it in accordance with changes of relative humidity; said belt being subject to elongation incident to fatigue caused by tension thereon, a movablepointen and a second hygroscopic belt connected under tension; with the lever and pointer and also subject to elongation by reason of fatigue resultant to tension thereon, the tension on the second belt being such that any move ment of the pointer resulting from fatigue in the first mentioned belt. is compensated forby relative adjustment of the lever and pointer due to corresponding fatigue in the second belt.

WORTH C. GOSS, 

